Data storage devices such as disk drives are commonly used in computers and other electronic devices for the storage and retrieval of data. Disk drives generally include a disk, a head connected to an actuator arm, and an actuator that controls the actuator arm to position the head over the disk. The actuator is usually controlled by a servomechanism that performs the operations of track seek to move the head from one track to another over the disk, and track following to attempt to keep the head over the center of a track during data reads and writes. If the head moves too far from the center of a track during a read operation, the operation must be suspended and retried, which reduces the data transfer rate of the disk drive. If the head moves too far from the center of a track during a write operation, data integrity may be adversely affected due to existing data on a wrong track being improperly overwritten and potentially lost.
When operating in various environments, a disk drive may be subject to disturbances that affect the head positioning by the servomechanism. For example, the environment may cause vibrations in the disk drive and there may also be external shocks that act upon the disk drive. Such vibrations and shocks may cause the actuator arm on which the head is located to oscillate and, thus, to move farther distances away from a track center. As disk drives become smaller and use lighter actuator arms, the problems caused by external disturbances become a larger concern.